That JATO solution would give an instantaneous clearance out of the vortex ring condition and (I guess) could be triggered by an FCS control follow-up circuit.
Scenario: Aircraft inadvertently enters AsymmVR during approach
i.e. 1. roll starts (within set FCS inputted parameters of airspeed, nacelle-tilt, Rate-of-descent and RadAlt height)
2. pilot makes normal instinctive differential-collective input to correct (as if for a gust-dropped wing)
3. FCS detects no roll-restorative response to side-stick applied in the correct sense (i.e. a decrease of some order of magnitude in the rolling moment, but in fact identifies an increase - which confirms that it's AsymmVR)
4. FCS decision is "Uh Oh, this is bad Kharma" and auto-fires "set 1" of emerg JATO (fuselage mounted and deployed together with gear extension ).
5. Aircraft accelerates out of vortex as roll-rate approaches bank of 60° (or thereabouts), regains differential collective controllability and aborts or does further circuit and approach (with "set 2" armed).
FCS = PFCS (primary flight control system) AFCS=Auto (both FBW aka fly-by-wire).
Flight control laws are all set by software and easily changed.
In fact, in order to gather useful empiric evidence of the AsymmVR condition, they would need to have something similar (to JATO) in order to ensure safety. i.e. it would probably be a sine qua non of any realistic trials and testing. When you think about the problems of replicating the condition in a full or quarter-scale tunnel, they are considerable. No tunnel is large enough that you can guarantee that the amount of air entrainment within a "stoked" vortex is representative of the free-flight unencapsulated open-air circulation.
The size of any such JATO kit need be no greater than 2000lbs of thrust for 15 seconds (= about 25kgs weight penalty per rocket, or about 100kgs overall). Perhaps simply having that four-simultaneous capability may also enable them to lower the safety margins in some other areas - to make up for it. It could also be used for emergency overweight STOVL departures (embassy bug-outs). Alternatively an underfuselage (over-fuselage) centre-line thrusting pair may do the job (and avoid the possibility of asymmetric firings). C130 had six JATO bottles per side but two per side would probably do the trick for the Osprey, two attached to each fuel sponson and firing a set at a time in the AsymmVR scenario.
Minus factor include the presence of explosive ordnance (particularly on a carrier), as well as the weight. A properly programmed FCS should preclude any nuisance firings.
There may be another vital VR factor at work here. The original XV-15 (upon which they did all the early proof-of-concept work) only had a 90 degree nacelle tilt capability. In the V-22 (all variants
AFAIK) they increased this to 95 degrees in order to be able to back it up on the ground or reverse whilst hover-taxiing (an important capability on a crowded flight-deck as well as on a crowded tarmac). It makes sense to me that they may have had the use of that rearwards thrusting capability in order to slow more quickly on the approach in helicopter mode (i.e. it's unlikely to have been "gated out" because they had no way of knowing that it could severely exacerbate any AsymmVR problem). To explain this last point, think of it as being very similar to VIFFing in the Harrier (Vectoring In Forward Flight that the Harrier uses in Air Combat Tactics in order to turn inside an adversary - or for braking on the ground). The only airborne use for it in the V-22 would be to make the plane-to-helo conversion a much later and swifter, more dynamic process (i.e. good for tactical surprise).
However, here's the rub. The use of it would make the Osprey much more likely to encounter VR, simply because it (VR) would not require a terribly steep approach angle or high rate of descent if 95 degrees of rotor-disc tilt was being utilised to kill energy (potential i.e. excess height or kinetic as in speed). Five degrees may not seem much but when you're talking about a standard 3 to 8 degree approach angle, it's a lot. It would be enough, particularly with a tailwind, to ensure that you were descending in your own "bad air" even at much higher speeds than you would expect to encounter VR. Normally they just would not need to use it unless, say, they had a need to quickly kill excess energy - for instance if, as in the Marana case, the wingman had overshot his leader and had very little time to get back in position. The more I think about it, the more that makes sense. So on four counts it would explain why they'd not encountered VR earlier in the test & eval program (at all):
a. Firstly, as we know, no-one had expected that the Osprey was susceptible to it and so no-one had suggested testing for it.
b. Any testing that may have been done earlier (on the XV-15) would have been reassuring, but being limited to 90 degrees of nacelle-rotor tilt, quite invalid regarding the Osprey.
c. It may be that the Osprey is vulnerable to AsymmVR only when 90 degrees tilt is exceeded) - such as when a very rapid correction is needed (as in the Marana aircraft's overshoot of the leader's abeam position).
d. Any testing done on the V-22 may have preceded the decision to go to 95 degrees (which was done for ground-handling reasons)
At the very least, I'd be asking whether there was any prohibition (or even caution) for use of >90 degrees of nacelle rotor-tilt airborne. Was there any idea as to what implications it could have? I'd guess the answer (through the "smoke and mirrors" reply that you'd get) would be quite revealing. I may be wrong but I suspect that it is neither "locked out" nor "detented" when airborne. I'd guess that neither the PFCS or AFCS software has any inhibitors programmed in either. Whether or not they'd tell you that is debatable. It may all of a sudden be not FOI'able and even a matter of National Security. But it's worth asking these questions.
What I'm saying here is that it could simply be yet another case of "unintended consequences". Life and aviation is choc-a-bloc with those hind-sightable instances of human fallibility.